1. Field
Various features relate to optical media converters and, in particular, to an optical media converter for use in commercial aircraft.
2. Background
Many aircraft employ aircraft data networks for routing and sharing data and control signals among various components of the aircraft. One example is the ARINC 629 system developed by The Boeing Company for use in, for example, the Boeing 777 family of long-range wide-body twin-engine jet airliners. (Note that the acronym ARINC refers to Aeronautical Radio, Incorporated.) Briefly, the ARINC 629 data bus is a time division multiplexed (TDM) system that includes multiple transmitters with broadcast-type, autonomous terminal access. Terminal access is autonomous with each terminal listening to the bus to wait for a quiet period to transmit. Only one terminal is transmits at a time. After a given terminal has transmitted, protocol timers ensure that the terminal does not transmit again until all other terminals have had a chance to transmit.
More specifically, ARINC 629 data bus transmits current mode waveforms along a data bus cable. Individual avionics subsystems are installed in line replaceable units (LRUs) that transmit signals onto the ARINC 629 data bus using a serial interface module (SIM) connected to the data bus via a twisted-pair stub cable and a current mode coupler (CMC.) The SIM operates in conjunction with a terminal controller of the LRU and generates electrical doublet signals that are routed to the CMC via the stub cable for conversion to current mode waveforms for transmission of the data bus cable of the ARINC 629 bus system. The stub cable is a balanced connection with, for example, a 100Ω characteristic impedance. The current-mode electrical signal is routed to each of a set other LRUs connected to the bus via respective CMCs and stub cables. However, the electrical cable plant necessary to support the current-mode transmission format contributes significant weight to the airframe.
Therefore, it would be desirable to provide an alternative to the aforementioned CMC that could receive the same doublet signals and power but would substantially reduce overall bus system weight. It would also be desirable that such a device would minimize overall avionics systems impacts while allowing for the use of existing terminal controllers and SIMs (i.e. that the alternative device would permit a retrofit with existing LRUs so that the LRUs need not be modified and re-certified.)